Relationship between the radial variation of ray characteristics and the stages of radial stem increment in Zelkova serrata

Abstract

We used ten discs from two Zelkova serrata trees - five discs from each tree at sampling heights of 1, 4, 7, 10, and 13 m above the ground - and investigated the radial variation in ray characteristics, i.e., ray area (cross-sectional area of rays on a tangential section), ray density (number of rays/mm2 on a tangential section), and ray proportion (the percentage of the area occupied by rays on a tangential section) and analyzed the pattern of variation with respect to the three stages (early, middle, and late) of radial stem increment as estimated using the Gompertz growth function. A juvenile-mature pattern of variation was observed in ray area and ray density. Ray area increased in the inner part of stem and fluctuated around a certain value in the outer part of the stem, and ray density decreased in the inner part of stem and tended to be constant in the outer part of the stem. The maturation age of ray density was similar to the age at the boundary between the early and the middle stages of radial stem increment, but ray area and ray proportion did not relate to the stages of radial stem increment. © 2010 The Japan Wood Research Society.